The present invention relates to a router apparatus using an ATM (Asynchronous Transfer Mode) switch to make routing of packets.
As a router apparatus using the ATM switch capable of exchanging signals at a high speed in the hardware manner to make routing of IP (Internet Protocol) packets, a product group named generically as IP switch made of IPSILON NETWORKS, Inc. is known.
FIG. 8 schematically illustrates this router apparatus.
As shown in FIG. 8, the router apparatus 1000 is connected among gateway apparatuses 2000 connected to LAN and WAN which adopt the IP.
The gateway apparatus 2000 receives IP packets from the LAN and WAN to make ATM cells and sends the ATM cells to the router apparatus 1000 while designating the defaulted VP and VC. An ATM switch 1100 of the router apparatus 1000 sends to an IP switch controller 1200 the ATM cells which designate the defaulted VP and VC. The IP switch controller 1200 restores the IP packets from the received ATM cells and investigates an address of the IP packets. The IP switch controller 1200 makes ATM cells which designate the defaulted VP and VC from the IP packets again and sends the ATM cells through the ATM switch 1100 to the gateway apparatus 2000 corresponding to the investigated address. The gateway apparatus which has received the ATM cells restores the IP packets from the ATM cells and sends the IP packets to the LAN and WAN connected thereto.
When the IP switch controller 1200 restores the IP packets from the ATM cells which designate the defaulted VP and VC received from the ATM switch 1100, the controller examines the service (FTP, HTTP, NFS, DNS, SMTP, POP, etc.) utilizing the IP packets, so that when it is the service having a heavy traffic, VP and VC which are new in a flow to which the IP packets belong are assigned to the gateway apparatus 2000 on the transmission side of the ATM cells. Further, when the gateway apparatus on the reception side of the ATM cells also receives from the router apparatus 1000 the ATM cells designating the defaulted VP and VC and restores the IP packets therefrom, the gateway apparatus examines the service utilizing the IP packets and when it is the service having a heavy traffic, VP and VC which are new in the flow to which the IP packets belong are assigned to the router apparatus 1000. The ATM switch 1100 is set so that the gateway apparatus 2000 on the reception side is caused to exchange the ATM cells received from the gateway apparatus 2000 on the transmission side and which designate the VP and VC assigned to the flow from the gateway apparatus 2000 on the transmission side as the ATM cells designating the VP and VC assigned to the flow to the gateway apparatus 2000 on the reception side.
When the gateway apparatus 2000 on the transmission side receives the assignment to the flow of the VP and VC, the ATM cells formed from the IP packets belonging to this flow are transmitted to the router apparatus while designating the assigned VP and VC.
The ATM switch 1100 of the router apparatus 1000 causes the gateway apparatus 2000 on the reception side to exchanges the ATM cells received and designating the VP and VC assigned to the flow from the gateway apparatus 2000 on the transmission side as the ATM cells designating the VP and VC assigned to the flow to the gateway apparatus 2000 on the reception side in accordance with setting.
Messages such as a request of the VP and VC and an assignment between the gateway apparatus 2000 and the IP switch controller 1200 of the router apparatus are stored in the ATM cells as the messages in accordance with a predetermined protocol named the IFMP (Ipsillon Flow Management. Protocol) to be transmitted and received, and the setting/release of contents of the exchange of the ATM cells in the ATM switch 1100 by the IP switch controller 1200 between the IP switch controller 1200 and the ATM switch 1100 of the router 1000 and control of transmission of the ATM cells designating the defaulted VP and VC in the ATM switch 1100 by the IP switch controller 1100 are stored in the ATM cells as the messages in accordance with a predetermined protocol named the GSMP (General Switch Management Protocol) to be transmitted and received.
According to the router apparatus described above, the router apparatus 1000 cannot perform traffic control (priority control and congestion control-of ATM cells) of the ATM cells in cooperation with the gateway apparatus 2000. Accordingly, when only the router apparatus 1000 attempts to guarantee the transfer band required in each flow, it is necessary to provide a buffer apparatus having a large capacity in the router apparatus. Further, since the router apparatus 1000 and the gateway apparatus 2000 must perform the traffic control independently, the transmission capacity cannot be used effectively as a whole.
Further, in the router apparatus, control signals such as a message conforming to the IFMP between the gateway apparatus 2000 and the IP switch controller 1200 of the router apparatus and a message conforming to the GSMP between the IP switch controller 1200 of the router apparatus and the ATM switch 1100 are all transmitted by means of the transmission path which is physically identical with the ATM cells. Accordingly, since the transmission band of the ATM cells cannot be assured to a level near to the maximum transmission capacity of the physical transmission path when more detailed control is performed, the transmission efficiency is lowered.
Accordingly, it is an object of the present invention to provide a router apparatus using an ATM switch and capable of performing various control such as traffic control more effectively.
In order to achieve the above object, according to the present invention, a router apparatus using an ATM switch to make routing of IP packets, comprises a multiplexer inputted with the IP packets for producing ATM cells from the inputted IP packets to multiplex the produced ATM cells, and an ATM switch unit for exchanging the ATM cells inputted from the multiplexer to produce the ATM cells to an ATM network, the multiplexer including shaping function for discarding the ATM cell in accordance with circumstances of the ATM network. Further, a router apparatus using an ATM switch to make routing of IP packets, comprises a multiplexer inputted with the IP packets for producing ATM cells from the inputted IP packets to multiplex the produced ATM cells, and an ATM switch unit for exchanging the ATM cells inputted from the multiplexer to produce the ATM cells to an ATM network, the multiplexer including a first interface including a line corresponding unit having an IP packet input unit for inputting the IP packets, an ATM cell producing unit for producing ATM cells with a mark indicative of a priority of the ATM cells in accordance with service of the inputted IP packet, and a shaping unit for discarding the ATM cell produced from the ATM cell producing unit in accordance with circumstances of the ATM network, and a data multiplexing unit for multiplexing the ATM cells processed by the shaping unit, and a second interface for synchronizing the ATM cells produced from the first interface.
For example, a router apparatus using an ATM switch to make routing of IP packets, comprises an ATM switch for exchanging ATM cells in accordance with VPI and VCI included in the ATM cells, a plurality of interface units connected to a network which transmits the IP packets, and an IP switch controller for making routing of the IP packets, each of the interface units including means for forming an ATM cell from a flow of the IP packets received from the connected network and transmitting to the ATM switch the ATM cell with specific VPI and VCI set to the flow in cooperation with the IP switch controller, means for receiving the ATM cells transmitted from the ATM switch and restoring the flow of the IP packets to transmit it to the connected network, means for setting specific VPI and VCI for the flow restored from the ATM cells received from the ATM switch in cooperation with the IP switch controller, and means for limiting transmission of the ATM packets to the ATM switch when traffic control is instructed from the IP switch controller, the IP switch controller including means for setting specific VPI and VCI for the flow of the IP packets in cooperation with the interface unit for source of the flow of the IP packets, setting specific VPI and VCI for the flow in cooperation with the interface unit for destination of the flow and setting contents of exchange of the ATM cells performed by the ATM switch so that the IP packets from the interface unit for source including the specific VPI and VCI set in cooperation with the interface unit for source are exchanged to the interface unit for destination as the ATM cells including VPI and VCI set in cooperation with the interface unit for destination, means for instructing the interface unit to perform traffic control when congestion occurs in the ATM switch or when occurrence of congestion is expected, and means for routing the ATM cells including the IP packets of the flow on the basis of an IP address included in the IP packet when the VPI and VCI for the flow are not set with respect to both of the interface unit for source and the interface unit for destination of the flow.
With such a router apparatus, when congestion occurs in the ATM switch or when there is a possibility that congestion occurs, transmission of the ATM cells can be limited in the interface unit at the previous stage of the ATM switch to thereby perform more effective traffic control.